1. Field of the Invention
This invention relates to spray valves and, more particularly, to a trigger actuated spray valve having a constant trigger actuating force regardless of fluid pressure and having a relatively simple and inexpensive construction for easy assembly.
2. Description of the Related Art
Many different types of spray valves are used for watering, dishwashing, vegetable spraying, and plant misting. Such spray valves are also used with shower heads for bathing. Typical spray valves are described in U.S. Pat. No. 3,588,040 and U.S. Pat. No. 4,187,986. As can be seen from these patents, such devices involve many parts and require careful assembly. These spray valves include a housing with an integral hollow waterway directing the flow of fluid from a valve inlet port to a valve outlet port. The valves operate by having a plunger or stem that fits into the waterway and seats against a rim inside the waterway, thereby plugging the waterway and blocking the flow of fluid. The plunger is actuated by a lever or knob located outside the waterway, the lever or knob being operated by the thumb of the user.
The plungers of these spray valves include a flexible, generally circular gasket placed on the plunger and in the waterway. When the plunger is seated in the waterway, the gasket is clamped against the internal rim, thereby stopping the flow of fluid. When the plunger is moved away from the waterway rim, fluid can flow past the gasket and toward the outlet port. A spring is used to bias the plunger into a normally closed position. A second gasket is provided to seal off the plunger and waterway from the trigger-actuating knob or lever. This gasket prevents the leakage of fluid around the plunger and out the knob. Fluid is not allowed to flow around this gasket regardless of the movement of the knob. During assembly, the moving parts, springs, gaskets and the like must be carefully positioned or the finished product will leak. Thus, the construction, manufacture, and assembly of these spray valves involves many parts and is quite complicated.
In starting and stopping fluid flow, the plunger operates by plugging or unplugging the waterway and therefore presents a surface normal to the flow of water. Thus, the plunger either works with or against the flow when moving from the stopped to open position. Therefore, the force needed to actuate the plunger varies with the flow pressure of the fluid. For spray valves that are used in conjunction with household plumbing, standardized testing procedures require testing of valve operation at water pressures of 20 psi and 125 psi.
Testing has shown that the force required to actuate the spray valve embodied in U.S. Pat. No. 3,588,040 varies from approximately 3 lbs. at 20 psi to approximately 71/2 lbs. at 125 psi. The spray valve embodied in U.S. Pat. No. 4,187,986 has an actuating pressure that varies from approximately 71/2 lbs. at 20 psi to approximately 3 lbs. at 125 psi. This is a large variation in the thumb pressure required for operation. Persons suffering from arthritis or from decreased hand strength find it difficult or impossible to operate the valves at the higher actuating pressures. It is desirable to provide a spray valve with a constant, moderate actuating pressure.
It is also desirable to provide a spray valve with multiple spray patterns. For example, these multiple spray patterns may include a coarse spray, a fine spray, and a mist spray. A multiple pattern spray valve is described in the above-referenced U.S. Pat. No. 4,187,986. This spray valve, however, achieves its multiple pattern sprays through a rather complex mechanism having a rotating and reciprocating plunger stem and a series of plates with many irregular surfaces. An innermost plate is provided with a plurality of orifices and projecting nubs, and is attached to the plunger stem. A second seal plate is provided with a plurality of openings. The innermost plate is rotated by a knob that is connected to the plate by a shaft passing through the housing, with the nubs seating in all of the openings except a set corresponding to a particular spray pattern. An outermost spray plate contains passages that communicate with the seal plate openings, different passages communicating with different sets of openings to provide the desired spray patterns. This construction is overly complex.